World Class Maintenance Management – The 12 Disciplines: 1, #1

By Rolly Angeles

Many industries today are struggling and living the day-to-day pressures of doing reactive maintenance and want a structured framework approach on how to achieve a level of World Class Maintenance Management. This book is specifically written for that purpose. This will be the first of a series of books I wrote and still writing about the 12 disciplines of maintenance.  Some highlights of this book include.

 

- Why Are Most Industries Reactive?
- Can Equipment Failures Be Eliminated?
- The Need for a World-Class Maintenance Management
- Understandfing the Basic, Intermediate, and Advance Disciplines  
- How to Make Training Work for your industry
- Selecting the Right KPI's for maintenance
- Why OEE Is Not a Perfect Measurement
- An Inconvenient Truth about Preventive Maintenance
- Survey on Top Problems on Preventive Maintenance
- Why Autonomous Maintenance Is Important
- RCM vs. TPM (which is the Best lb. for lb.) Improvement Strategy
- Integrating RCM into the TPM Process
- Why TPM is Hard to Implement
- My TPM Experience - A Successful Failure
- Why Many Root Cause Initiatives Fail
- The Lifeblood of Root Cause Failure Analysis
- Where Do We End Our Probe in Root Cause Analysis?
- What does Will It take for the Maintenance to Get There?
- What Does It Take to Change People?  And many more.  

 

Many industries today can consider themselves to have a world-class quality on their product, a world-class service provider, a world-class safety, or you can declare that your industry has world-class facilities, but speaking about world-class maintenance is a different story and only a few companies ever reach this stage. While many industries will try, only the thoroughbred will understand and succeed.  This book is written for every maintenance out there who are seeking ways to improve their equipment and assets reliability and maintainability to optimize their operations and dramatically reduce their maintenance costs. 

• Language: English
• Publisher: Rolly Angeles
• Release date: Jun 7, 2021
• ISBN: 9798201149123

Book preview

Introduction: World Class Maintenance Management Explained

1.1: Why Most Industries Are Reactive

HAVE YOU EVER FIGURED out why your equipment keeps on failing despite the very best efforts on Preventive Maintenance?  Below are lists of questions, and try to answer them as honestly as possible on your own.  If you answer yes to most of these questions, then you definitely need to read this book.

• You are always pressed for time and do not have the luxury to attend training because your boss or schedule will simply not allow you to do so.

• Are you instructed to turn on your cell or mobile phone at night when you are at home to receive late calls from other shifts wanting you to go to the plant in the middle of the night or early morning for a problem that they cannot seem to fix?

• Does maintenance complain that they are always outnumbered by their everyday failures and about the lack of labor and manpower resources to fix their day-to-day failures?

• Do you have to sacrifice some family time to keep working overtime, and when you return home, everyone is asleep?  Your cold food is waiting for you at the table.

• When equipment is newly overhauled or has just been into a major Preventive Maintenance shutdown, do you ever wonder why operators tell you that this equipment is better off if you had not performed your regular scheduled Preventive Maintenance?  They seem to have some difficulties running the equipment smoothly during start-up?

• Do you need to cannibalize some parts from other stationary equipment since there is no stock or spare around the stockroom?  Do you do this all the time?

• Now, this is the worst part.  Do you have nightmares of your work or your boss yelling at you about the root cause that wakes you up in the middle of the night?

If you answer yes to almost all of these questions, then do not be surprised since you are not alone on this planet.  Let me explain it to you.  When I studied all these things about reliability and maintenance, I used to have an old friend and mentor. I called him Mang Tibo (In our country, Mang represents an old person.)  He worked for a very long time in the industry.  They retired him because he was old.  I guess that was the trend.  Anyway, I remember asking him about what was the best maintenance strategy that the industry can adopt, and he told me that if I wanted to know the answer to my question, he said to come and follow him.

I took his advice, and we walked and sat down in a park near his place.  The park had a basketball court, and he asked me to sit down and watch the game because his team was playing, and there was an ongoing league at that time.  We sat and watched the game, and not a single word from him was ever spoken about the question raised; instead, as we were sitting on a bench, you can feel his enthusiasm about the game shouting words of support to his team.  We just watched the game from start to finish.  It was a close game, and his team won.  It was getting a little bit dark, and he told me to go home since my place was a couple of hours away. I asked him why we watched this game.  I thought he was going to answer my question about the best maintenance strategy to adopt.  Calmly, he looked at me, smiled, and said, If you watched the game carefully, then you have already answered your own question. I was shocked since I had no idea what he meant or if he was making any sense at all.  I usually give this story to people I teach and wonder if they can figure it out themselves. I guess, just like me, they find a hard time what that old man was talking about or if he was making some sense after all.

As I was about to leave, he explained that maintenance is not different from playing a basketball game.  A team mainly composes of two guards, two forwards, and one center.  He asked me what if I place five centers in a team and no forward or guards in it.  Is it a balanced team?  I said no, of course. It is like assuming that all parts will eventually wear out, which is unlikely to happen since only around a small percentage of most equipment parts and components will have a wear-out pattern.  Imagine putting a basketball team of 5 people who are all guards.  Again is it a balanced team?   It is like assuming that all parts will randomly fail; again, there is still infant mortality and wear-out failures.  So you see, just like basketball, maintenance is a game of balance.  Therefore, the best maintenance strategy to adopt is not about preventing or applying the best predictive maintenance strategy, but it is about creating a balance and understanding when to use the different strategies simultaneously when you need it since every failure has its own unique pattern and consequences.  Therefore, just like in basketball, the best maintenance strategy to adopt should be based upon the consequences of every single failure itself and not just confined to a single strategy.

Putting too much effort into your current Preventive Maintenance activities will only lead you to more failures since PM can only accommodate failures that have worn out or age-related patterns.  This is like putting five centers in one basketball team.  Your team will not work, and the players will not blend.  I believe this is one of the main reasons most industries are reactive since they place all their center players in one team.  They assume that their current Preventive Maintenance structure will capture all kinds of failures. Eventually, they are wrong in every way.  Therefore, instead of preventing failure, most industries today perform their maintenance on firefighting or reactive mode.  Fix it when it fails syndrome.  Others call this the Band-Aid or Firefighting Therapy.  This generation of maintenance evolved during the 1940’s way before the Japanese bombed Pearl Harbor. Equipment at that time was simple.  Hence this type of maintenance did not seem to make any effect on production after all.  However, as time passed by, more and more developments had been made.  Equipment is now highly automated, complex, and modernized to perform the task required, but sad to say, when we speak about the way we maintain, I think nothing or little had changed so far. Most companies hire and look for maintenance people with extreme experience in repairing the equipment and not on the maintenance system, which is why there are only a few people with such knowledge and understanding of the maintenance strategy itself.

Maybe your industry has been religiously adopting the concept of Preventive Maintenance, and standards are in place.  Your group has every detail from overhauling and replacement of parts to be performed on a specific set of time indicated in the equipment.  Besides, since we find it hard to satisfy everyone, most especially our customers, from time to time, something has often been added with our never-ending growing list of PM checklists since they thought that it is the right thing to do. I call this the Add on PM Checklists Syndrome.  Before the maintenance, the checklist consists of around 15 activities when the equipment was newly commissioned in the plant, but today the checklist of things to do rounds up to more than 150 items. Does increasing the number of activities on Preventive Maintenance guarantee higher reliability on the part of the equipment, or is it just the other way around?  Perhaps doing more maintenance on our equipment will do us more harm than good in the end.  I have researched and studied possibly the best maintenance strategies to adopt through the years, such as Total Productive Maintenance, Reliability-Centered Maintenance, Lubrication Strategies, and Root Cause Failure Analysis Tribology Contamination Control, and other related maintenance management courses.  It seems that as I dwell more on the subject of maintenance and reliability, the more it becomes clear on what maintenance can do and cannot do with our equipment.  We simply need to understand things before providing a holistic approach to our maintenance strategy, and maintenance needs to walk into this thin line if they are dead serious about improving their equipment.  But the problem with most people in industries is that they abuse this strategy, which is Preventive Maintenance.

1.2: Can Equipment Failures Be Eliminated?

FAILURES ARE DIVERSIFIED by nature.  When I ask people their thoughts if all their equipment failures can be eliminated, some say yes, and others simply say that they can only eliminate a fraction of them.  Hence, I tried to be a little bit more specific and rephrased my question by asking which of the following statements they think would be more appropriate, relevant, meaningful, and much more realistic:

• First, we can eliminate failures by analyzing them through Root Cause Failure Analysis.

• Second, we cannot eliminate the likelihood of failure, but rather, we can only prevent or predict the timing of failure from occurring on its own.

• Third, we can eliminate failures, and our goal is to zero out the breakdown.

• Fourth, failures cannot be eliminated.  The best that maintenance can do is to anticipate, delay, prolong, or control the process of failure from occurring on its own.

First, not all failures are created equal; every single failure will have its own unique set of consequences.  People have different views or interpretations of what failure is all about or when to call it a failure. A failure can differ from the operations, maintenance, and safety point of view.  Sometimes confusion arises, so we call it a failure.  Hence, I would like to explain what failure is all about.  Technically, when operators call maintenance to fix their equipment, it is not the equipment that failed after all; it is a part, component, or system that failed in their equipment.  Failure is when an item, spare part, or system in the equipment fails to perform its desired function.  Therefore, to answer these questions:

First: We can definitely eliminate failures by analyzing them through RCFA:  Wrong! Failures cannot be eliminated by analyzing them through RCFA or RCA.  We must consider various possible causes of failure occurrences, and every single failure has its own unique causes.  When we treat a single cause, it is like that the same part will fail again due to a different cause.  Remember, when we speak about Root Cause Failure Analysis, we are dealing with evidence of what really has caused the part to fail and not all the probable causes or failure modes that might have caused the part to fail.

A bearing can fail for a variety of reasons, and taking care only of one single cause (perhaps the analysis indicates that the inner raceway of the bearing shows failure is attributed to lubrication) will not eliminate its recurrence since it can fail in the future due to some other reasons such as false brinelling, pitting, fatigue, spalling, misalignment, contamination, careless handling or lack of lubrication and much more.

Second: We cannot eliminate the likelihood of failure, but we can only prevent or predict the failure from occurring.  Yes, it is possible to prevent some failures. This is true for age-related failures or parts and components which inhibit some sort of wear-out mode.  These parts constitute around 15% to 20% of the overall equipment failures for the airline industry.  Perhaps, this is slightly higher for land industries.  Likewise, some failures can be predicted, especially those that show signs of potential failures, or they are on the verge of falling out, but this is not the maintenance goal.  If a bearing fails prematurely, we can predict that it is on the verge of failing, but the bearing's life has not been reached and maximized at all.  We might have some success in advising operations about it, but we should not stop here.  Data from Predictive Maintenance are very useful in analyzing component failures. Predictive maintenance is one-step forward towards being proactive.  However, not all failures can be predicted nor prevented.

Third: Failures can be eliminated, and the goal is to zero out breakdowns.  Wrong! Some think that when we have experienced zero breakdowns or have reduced failure tremendously, as seen on our breakdown indices for the past couple of years, we think that we have eliminated the failure completely, but technically speaking, come to think of it, have we really eliminated the likelihood of failure or have we just delayed the failure process from occurring, because of our good system of maintenance?  Just try to think of buying a second-hand car.  Driving it and giving it your best maintenance ever.  Eventually, many parts are subject to wearing out, and when parts wear out, and then they have actually and eventually failed, haven’t they?

Fourth: Failures cannot be eliminated.  The best that maintenance can do is to anticipate, prolong, or delay the process of failure itself from occurring.  Correct!  We must not be misled that maintenance can eliminate failures.  Failures cannot be eliminated.  They will happen.  The best that maintenance can do is to anticipate failure, delay its process, control the timing of failure or eventually prolong the occurrence of failure from happening, yet in the end, failure and breakdowns will still likely occur in our equipment, and we must be ready for them.  Maintenance must focus on something more realistic and not ideological in nature.

Let me provide a clearer example.  A small plant has around 100 pieces of equipment or more, and each piece of equipment is composed of around 20,000 parts.  This plant has ten people working in the maintenance department to address the issue of equipment failure.  Some people are deployed to perform maintenance work.  They have some form of Preventive Maintenance.  They sort of schedule their equipment from time to time for some form of equipment replacements and overhauls.  Others perform some inspections on their equipment from time to time.  They even deploy a group called sustaining people or other names to perform repairs and troubleshooting.  There are modifications, and they redesign their equipment.  However, despite the very best efforts, the machine still fails.  The truth is all equipment is vulnerable to failure.  Therefore, the aim of maintenance is to control failure's timing to select or perform a more suitable task before a failure happens.  The best that we can do to our equipment will be to extend the length of time between failures, prevent the failures by replacing the most problematic components before they fail, monitor failures by detecting signs and symptoms that they are on the verge of failing.  This is possible by determining the condition of the equipment.  Making the equipment more reliable is about extending the useful life and Mean Time Between Failure (MTBF) and preventing failures by replacing the part and components that are most likely on the verge of failing.

Failures cannot be eliminated, and failures vary in consequences. The best that maintenance and reliability people can do is delay the process and control the timing of failure, but eventually and inevitably expect failure to occur in the equipment.  A no failure situation in your equipment is just temporary because of the good system of maintenance. The truth is you are just delaying the process of failures.  I have been in the field of TPM for so many years, and its goal of zeroing out unplanned breakdowns is somewhat idealistic and, in its technical sense, next to impossible if we really understand how parts behave. When a part wears out, in its technical sense, it has failed. Hence, we are not really eliminating failure itself but just doing the best we can to prolong the part or component's life or extend its natural lifespan.  Hence, we know what we can do and cannot do with our equipment by understanding them.  But before going further, let us learn the diversity of failures by understanding their patterns, classifications, types, and occurrence before adopting a more structured and robust maintenance strategy in our equipment.

1.3: Patterns of Failure (How Parts Behave)

FAILURE OF PARTS CAN be categorized into the following patterns: infant mortality, random or age-related failures.  These failures can be illustrated in Figure 1, which is known as the bathtub curve.  The bathtub curve starts with a high incidence of infant mortality failure, followed by a constant or gradual increase in the conditional probability of failure and ending up in wear out or age-related zone.

FIGURE 1.1: THE BATHTUB Curve

Infant Mortality Failures occur at the beginning of life. Others refer to them as commissioning failures, start-up failures, or debugging failures.  Many factors affect Infant Mortality Failures, which include poor equipment design, poor quality manufacture, incorrect installation, incorrect commissioning, incorrect operation, poor set-up and conversion practices, unnecessary maintenance, slips and lapses, human errors, bad workmanship, and excessive Preventive Maintenance.  The case of Infant Mortality Failure, Pattern F of the Six Failure Pattern, starts with a high incidence of early failures, which eventually drops to a constant or very slow increase in the conditional probability of failure ending in no wear-out zone.  Operators often say kiddingly that if you have not performed your regular overhauling and replacement on this piece of equipment, it will be running without any problem.  Most operators complain about having a hard time starting their equipment after a major overhaul is performed.  But isn’t it true that the main purpose of scheduled maintenance is to ensure that the equipment performs as expected, but the opposite seems to happen whenever maintenance does something on the equipment?  Is it profound?  NO! You are just a victim of what you call Infant Mortality Failures.  You don’t need to be a Nobel Prize winner to figure this out.  All you need is a modicum of common sense.  From a maintenance point of view, their pride and ego hurt, but it is a fact of life that we must live with and with all humility must understand and admit.  Infant Mortality Failures are caused by human errors and intrusive or forced maintenance carried on with the equipment in almost all cases.  In fact, many things can go wrong when we try to dismantle equipment for overhauling purposes because our belief is that we can put it back together in one piece just the way it used to be.  Human errors such as slips and lapses can occur on the part of the maintenance performing the overhauls.  The message of infant mortality failures is simple.  If your people are equipped with the right knowledge, skill, and have the right tools to perform the job of replacement and overhauls, then go ahead and proceed, but if you have the slightest doubt of bringing it back altogether in one piece, then think again before dismantling it.  It might be a good idea not to disturb the equipment, after all.

Studies done by the pioneers of RCM, Stanley Nowlan and Howard Heap, for the civil aircraft industry, revealed that 68% of items that failed in airline industries conformed to pattern F, which is the case of Infant Mortality Failures.  An example of some of the benefits achieved from this learning on infant mortality failures by the civil aircraft industry was the dramatic reduction in their scheduled overhauls in their DC-8 aircraft in which 339 items were previously scheduled for overhaul and were trimmed down to only seven items for their DC-10, which is a more complex and modern aircraft.  One of the items that were no longer subjected to overhaul was their turbine engines.  Another milestone in their research was a reduction in inspection for the United Airlines Boeing 747, where they spent around four million man-hours of inspection compared to around sixty-six thousand man-hours on structural inspections for their DC-8 aircraft.  Today's airplanes are bigger, more complex, better automated, and, most of all, safer to travel than those used fifty years ago. Truly, it had been a remarkable achievement for the airline industry, which saved millions of dollars on maintenance without compromising safety and improving reliability.  However, the greatest benefit learned from Infant Mortality Failures by the airline industry is that it saves lives.

The Lesser the Maintenance, the Better

Performing too much overhaul on the equipment to comply with PM specs and activities do not guarantee that the equipment will be reliable in the future.  It is similar to the logic that a fat child is not exactly a healthy child.  Healthy and fat are not synonymous.  There are cases when a child is more prone to disease and sickness when he or she is fat; on the other hand, eating plenty of food each meal is not an indication of a healthy person.  Eating the right balance food each meal can make us healthy; similar things hold true with maintenance.  The more activities we perform on our equipment, the more likely it will fail and induce what we call infant mortality failures.  I have seen many cases that when equipment is subjected to an overhaul and returned to the operations, operators complain about having a hard time running the equipment.  Some maintenance tends to forget some small parts of the equipment.  Most people are shocked when I say that the more PM you perform on your equipment, the more problems you will encounter, while the less PM you perform, the fewer problems you will encounter.  I never said no PM means a problem.  PM will always have a place in the maintenance function.  If Infant Mortality Failure exists, the question to rise is, can we eliminate it?  Many factors contribute to infant mortality failure, and it is impossible to eliminate them.  The best we can do is to reduce its likelihood of occurring.  Let us look at this perspective on the most common causes of infant mortality failures.

DESIGN STAGE

No equipment is perfect by design.  There is always a design weakness or flaw attributed to it.  Some parts tend to fail prematurely during commissioning and even in actual operation.  We need to identify these parts and conduct a physical investigation and Root Cause Failure Analysis to why these parts keep on failing prematurely.  Only when we truly understand the cause of failure can we recommend a redesign or modification, such as changing its shape, size, or strength of materials.

Commissioning Stage

Problems occur during the commissioning of equipment in our plant.  Either some human error was involved during set-up or start-up.  Infant Mortality Failures are the reasons why vendors and manufacturers provide some form of warranty period for their equipment, most especially during commissioning and start-up activities. A lot of debugging during the equipment's commissioning stages is necessary before it can finally be endorsed to operations.

Scheduled Overhauls and Replacement

When equipment is operational, infant mortality failures occur more frequently when maintenance intervenes with the equipment to perform routine time-based scheduled overhauls and replacements. There is always the assumption that when maintenance dismantles the equipment, they can confidently put it back together.  This book does not intend to discredit Preventive Maintenance but rather educate everyone who performs overhauls on the equipment who can introduce infant mortality failures into an otherwise stable system.  There are many ways to check the condition of the equipment without dismantling it.  These techniques are known as Predictive Maintenance.  For example, instead of overhauling an engine, why not check its oil.  Normally, when the equipment is not in good shape and needs reconditioning and overhauling, check the oil condition, especially the metal contents.  Metals present in the oil can indicate which part is actually on the verge of failing so that maintenance can pinpoint with accuracy which parts to remedy.

With this in mind, we should rethink again our strategy on what activities must be included and excluded when performing PM overhauls and replacement on a scheduled frequency because this is when the equipment is more vulnerable to infant mortality failures.  Perhaps, we might not get a high score on our PM completion rate, and for manufacturing, there are chances when Quality Control will provide us some form of non-conformance tickets to the maintenance department because some parts of Preventive Maintenance are deliberately ignored.  Suppose we intentionally missed PM due to the high incidence of Infant Mortality Failures in the plant; in that case, I believe the reasons are valid and that there are some parts of our equipment that should remain undisturbed.

Random failures occur at any given period.  This means that the probability that an item will fail in any one period is likely the same as it is in any other given time.  The conditional probability of failure remains constant.   In figure 1.3, Case 1 indicates random failures since the frequency of occurrence on failures on the bearing occurs every year. In this case, replacing the bearing on a scheduled Preventive Maintenance or time-dominated frequency will not be the best solution.  When the failure is random in nature, this is when Preventive Maintenance will be at its weakest point.

To further illustrate my point on random failures, imagine that you are driving your car, and a small piece of rock hits your windshield, which causes a very small fracture.  My question with you is, when do you think the second rock will hit your windshield again?  The answer will always be in the form of a wild guess.  If this event happens many times, calculating through statistical means or using some Weibull Analysis can provide us some basis, but it will not determine the exact time and place for the next rock to hit your car.  To know the occurrence of random failures is like catching lightning with a Polaroid camera on that precise second it shows up.  Why use a Polaroid camera where one can use a video camera to capture the lightning itself.  Random failures do not adhere to any specific age, and their occurrence can be expected anytime.

Figure 1.3 indicates a list of failure distribution on the same bearing that failed during operations for nine consecutive years.  Every time the same bearing failed, maintenance religiously recorded the date when it failed in the history book.  In the figure, we speak of the same bearing and that our history records showed that five bearings failed during the first year, 15 failures in the second year, and so on.  No bearings ever achieved a life of more than 8 years.  With this distribution, when is the best time to replace this bearing?  If you answer in the first year, your maintenance effort would be very costly since most of the bearings will last for more than one year.  This means that when the bearing will reach a life of 4 years, and we replace it in the first year, we throw 3 years of the good life on the bearing because we are replacing good parts that are not yet on the verge of failing.  Suppose you answer that the best time to replace the bearing will be in the 8th year; we have reactive maintenance or likely to experience a run-to-fail situation in our operations.  Perhaps this would be a good idea if the consequences of failure can be limited to the cost of repair or redundancy is in place. However, if this is not the case, then a run-to-fail situation would not possibly be the best option.  No amount of scheduled maintenance can fully address a case of random failure.  Therefore, if this is the case you are experiencing with some of the parts in your equipment, the following are some of the options you may want to adopt to address the case of random failures:

USE OF PREDICTIVE MAINTENANCE Strategy

Predictive Maintenance is valid if the part whose failure is random possesses a potential failure.  A potential failure is actually a symptom or indication that a part is on the verge of failing, although it is not yet in its failed state, or it has not yet reached its functional failure. When a part provides excessive sound, noise, heat, vibration, and then these are all signs of potential failure that can be detected with an ailing bearing.  Predictive Maintenance instruments can help us determine the potential failure of certain parts of the equipment, such as this bearing in our case.  Once a potential failure is spotted, we need to determine the P-F interval and perform some maintenance before reaching its final stage, which is the functional failure.

Use of Root Cause Failure Analysis

We can try to understand the causes of failures through Root Cause Failure Analysis.  Failures happen for a specific reason, and there is always a cause-and-effect relationship.  Most people's mistake is jumping to redesign or modification without understanding the causes behind the failure itself, only to realize that a newborn problem emerges because of the redesign and modification.  Performing a thorough investigation will explain why the failure occurred in the first place based on its evidence. Hence, when performing a Root Cause Failure Analysis, the probe's depth should always end up on the Latent Cause of Failure.

Run To Fail Strategy

This is feasible and applicable to use if the consequence of failure will be limited to the direct cost of failure and will not compromise safety, environment, and operations.  This is also applicable if the system has backup or redundancy, making the failure tolerable and safe, as in the Airline Industry case.  When you are traveling by plane and the pilot senses that something has failed when the plane is airborne, the pilot cannot simply ask for any volunteer from the passengers and provide them a rope to check the engine's condition or perform some sort of Predictive Maintenance outside the plane.  They will allow failure to happen simply because they have some form of back-up or redundancy, which makes operation safe even with the presence of failure.

Hence, for failures, which are random in nature, never use Preventive Maintenance or a time-based strategy because this is where this strategy will be useless and weak.  Applicability of using Preventive Maintenance overhauls and replacement is only applicable to parts that conform to wear-out or age-related patterns.  Just remember, the more automated, complex, and complicated your equipment is, the more cases of infant and random failures will be experienced and encountered.  What is important is understanding which maintenance tasks are the most suitable and feasible to use.

Wear-out Failures or Age-Related Failures mean that parts will eventually survive to their guaranteed age span.  Age specified may be running hours, time, number of strokes, revolutions, number of stress applied, or any other form.  The best maintenance strategy to use on this type of failure will be to identify when most parts will start to wear out and apply Preventive Maintenance.  This is the easiest failure to address but the least common failure among the six failure patterns.

In boxing, as the boxers aged, they get closer and closer to retirement. They begin to lose their skills and speed, which they used to have during their prime.  We have legendary boxers such as Muhammad Ali losing to Larry Holmes, Larry Holmes losing to a younger boxer, Iron Mike Tyson, Mike Tyson losing to a taller boxer Lennox Lewis and just recently in 2008,  Oscar The Golden Boy dela Hoya losing to my country’s very own  Manny Pacman Pacquiao.  As Pacquiao’s Coach, Freddie Roach, kiddingly said to Oscar dela Hoya during their conference match that he found a toy gun and it seemed that the trigger is no longer working and gave the toy gun to Oscar dela Hoya and said, maybe this toy gun belongs to you since you can’t pull the trigger anymore.  These great boxers lose simply because time has caught up with them.  These boxers have their fine moments in boxing and are considered among the greatest.  Their names are in the Boxing Hall of Fame.  Even if the mind and heart still want them to continue fighting, they cannot hold through with their body.  They will always be outclassed by younger boxers.  We have witnessed legends in boxing lose to a much younger, stronger, and faster fighter.  Age has something to do with them. The stress they had undergone throughout their boxing career had exceeded the strength of their body.  Likewise, when the stress exceeds the strength of the materials, wear eventually takes place.  As in boxing, these legends had eventually worn out.  I think the only boxer that defies this logic is Rocky Balboa and George Foreman.

1.4: Classification of Failures

HIDDEN FAILURES DO not become evident to the operator or maintenance when it occurs on its own, while evident failures will become evident to the operator and maintenance people when it occurs on its own.  Let us refer to the three identical pumps in figure 1.4.  One pump is located in Area A, which is a stand-alone pump.  It has no standby or back-up. When this pump fails, the fluid flow will definitely stop, and the operation will simply be affected due to the pump's failure.  In this case, the failure of pump A is evident.  Area B is installed with the same rated capacity as pump A and discharging the same fluid in another place.  The difference is that this pump is equipped with a stand-by pump.  If pump B fails, the flow will automatically be transferred to pump C.  If we ask ourselves, will pump B's failure on its own become hidden or evident?  The answer is it is still evident since the operator would know that once this happens, then pump C would be activated.  In the operator’s mind, pump C will only run if pump B fails, making it evident.  But what if pump B is running and, for some reason, pump C fails or stuck-up since it has not been used for a very long time?  Will the operators know in any instance that pump C has failed if the duty pump, which is pump B, is running?  The answer is that the failure of pump C is hidden since we can only determine its failure if the duty pump B has failed, and this is the only time we will know that the standby pump has failed in the first place.

Hence, if we are going to derive the most suitable tasks for each pump, I say that for pump A the most feasible task to use is Predictive or Preventive Maintenance since if this pump fails, it will affect operations since this is a stand-alone pump in the first place, while we can run to fail Pump B since if it fails operations won’t be affected since we have a back-up pump in place.  For Pump C, a standby pump, we can occasionally run it to check if it is still running.  This simply explains that the conditions in which equipment is being operated should be taken into account in determining the most feasible maintenance tasks and that similar equipment might require different tasks because the consequence of failure varies.  This is one of the problems with Preventive Maintenance since they assume that similar equipment will have similar maintenance tasks. The equipment might be similar, but the condition in which the equipment is being operated may not be similar.  Hidden failures will only become evident if the part, component, or system they are protecting has eventually failed in the first place.  This is most especially true for protective devices or redundant functions.  What we are avoiding will be a chance of multiple failures where the protected function has failed simply because the protective device is in a failed state.  The only way for us to determine that a hidden failure has occurred is if another failure will occur due to this.  Consider the following cases of hidden and evident failures to understand this point